- Joined
- Feb 13, 2017
- Messages
- 2,138
Having found your post an hour or so after it was posted, I wanted to give it some thought and take a nap before answering. You obviously know what you're doing, to some extent. So my first question is if you already have a machine. Either a lathe or a mill, it doesn't matter. It's simply to point you in the right direction. I have a Craftsman lathe (Atlas build) as well as an Asian machine. (Grizzly) The Atlas machine has 16DP 14-1/2*PA gears. The Asian has Modulus 1 (25.4 DP) 20*PA. As it happens, I also run an Atlas mill, 24DP (I think) and an Asian vertical mill which also has Mod.1 gears. The point is to study your machine(s) and use the same gear pattern. Even Asian gear cutters from eBay cost a pretty penny for a set. You want something that will be useful in the future.
I would prefer a smaller gear (~Mod.1) for a benchtop machine. 16 DP gears are large enough to be cumbersome for a small (less than wheelbarrow sized) project. It all depends on what, if any, machines you already have. Pressure angle (PA) is a matter of what gear you decide on. Diametrical gears more commonly use 14-1/2 degrees for lower friction. Modulus gears more commonly use 20 degrees for strength. Like above, it would depend on your own machine(s) as reference. Gear cutters can be found for more esoteric pressure angles, but the cost can be much higher. I'd say stick to the more common design for cost savings alone.
Some time back, I repaired a "lemon squeezer" for a friend that had a small cafe'. Your project sounds a lot like that one. The gear was (probably) a Mod.1.25, call it 18 or 20 DP. All I remember was the gears were smaller than my Atlas and larger than my Asian machine. I made the replacement the hard way (without a cutter) from brass. I don't know how it stood up. I have a small (1/2 Ton) arbor press. It has a rack and pinion about the size of my Atlas lathe, but I figure it's metric. In any case, it would be way over kill for a capper. I would say look to eBay for a "button press" as a starter idea. The price I saw was low enough to make a good pattern.
Material is another concern of relevance. Gears can be made from paper, wood, plastic, non-ferrous metal, all the way up to steel alloys. I worked with a fellow that was building a replica clock from paper. Gluing up a sheet at a time to make the gears. But for automotive steering, one would want high quality steel. For the first timer, aluminium would be a good choice for something not critical. Fairly cheap, and easy to work. And easy to make another when you make a mistake. My Atlas has some plastic thread cutting gears, and some ZAMAK. External gears are ZAMAK, internal(read high load) gears are steel. Some may be cast iron, I don't know and it really doesn't matter.
Cutting a rack has some off the wall requirements regarding length. There have been several methods given above. There's a lot of knowledge on this site. If I needed a custom rack, I would build it on my shaper, using an involute cutter in a custom made tool holder. You're on your own there. I have a large quantity of racks salvaged from the aircraft industry. I don't know the tooth size but I suspect they are metric. They appear to be Mod.1, but I've never used one so never pursued it any further. Just a situation where they were cheap because they weren't selling. I might need one some day, or Wife will sell for scrap when I don't matter any more.
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I would prefer a smaller gear (~Mod.1) for a benchtop machine. 16 DP gears are large enough to be cumbersome for a small (less than wheelbarrow sized) project. It all depends on what, if any, machines you already have. Pressure angle (PA) is a matter of what gear you decide on. Diametrical gears more commonly use 14-1/2 degrees for lower friction. Modulus gears more commonly use 20 degrees for strength. Like above, it would depend on your own machine(s) as reference. Gear cutters can be found for more esoteric pressure angles, but the cost can be much higher. I'd say stick to the more common design for cost savings alone.
Some time back, I repaired a "lemon squeezer" for a friend that had a small cafe'. Your project sounds a lot like that one. The gear was (probably) a Mod.1.25, call it 18 or 20 DP. All I remember was the gears were smaller than my Atlas and larger than my Asian machine. I made the replacement the hard way (without a cutter) from brass. I don't know how it stood up. I have a small (1/2 Ton) arbor press. It has a rack and pinion about the size of my Atlas lathe, but I figure it's metric. In any case, it would be way over kill for a capper. I would say look to eBay for a "button press" as a starter idea. The price I saw was low enough to make a good pattern.
Material is another concern of relevance. Gears can be made from paper, wood, plastic, non-ferrous metal, all the way up to steel alloys. I worked with a fellow that was building a replica clock from paper. Gluing up a sheet at a time to make the gears. But for automotive steering, one would want high quality steel. For the first timer, aluminium would be a good choice for something not critical. Fairly cheap, and easy to work. And easy to make another when you make a mistake. My Atlas has some plastic thread cutting gears, and some ZAMAK. External gears are ZAMAK, internal(read high load) gears are steel. Some may be cast iron, I don't know and it really doesn't matter.
Cutting a rack has some off the wall requirements regarding length. There have been several methods given above. There's a lot of knowledge on this site. If I needed a custom rack, I would build it on my shaper, using an involute cutter in a custom made tool holder. You're on your own there. I have a large quantity of racks salvaged from the aircraft industry. I don't know the tooth size but I suspect they are metric. They appear to be Mod.1, but I've never used one so never pursued it any further. Just a situation where they were cheap because they weren't selling. I might need one some day, or Wife will sell for scrap when I don't matter any more.
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